Crimped thermoplastic filament having a two phase cross-section

ABSTRACT

AN IMPROVED CRIMPED FILAMENT OF THERMOPLASTIC SYNTHETIC HIGH POLYMER OF THE INVENTION IS COMPOSED OF NONCONJUGATED STRUCTURE HAVING TWO DIFFERENT PHASES IN CROSS SECTION OF SAID FILAMENT. THE ABOVE-MENTIONED TWO DIFFERENT PHASES IN CROSS SECTION OF THE FILAMENT IS DEFINED BY THE DIFFERENCE IN DYEABILITY OR REFRACTION INDEX. THE CRIMPED FILAMENT OF THE INVENTION IS PROVIDED WITH THE OUTSIDE ROUGHENED SURFACE HAVING NUMEROUS FINE PIT-LIKE PORTIONS. THE PROCESS FOR MANUFACTURING THE CRIMPED FIBER OF THE INVENTION IS ALSO DISCLOSED.

Aug. 17, I971 TERUM|CH| 0 0 EI'AL 3,600,271

CRIMPED THERMOPLASTIC FILAMENT HAVING A TWO PHASE CROSS-SECTION Filed Nov. 28, 1967 3 Sheets-Sheet 1 Aug. 17, 1971 TERUMlCH] 0 0 ETAL 3,600,271

CRIMPED THERMOP LAMENT LASTIG FI HAVING A TWO PHASE CROSS-SECTION Filed Nov. 28, 1967 3 Sheets-Sheet 2 F/ J 2c Hg. 20

PR'OR ART PRIOR ART Aug. 17, 1971 Filed Nov. 28, 1967 LOOP LENGTH OF CRIMP LOAD TERUMICHI ONO ETA!- 3,600,271

GRIMPED THERMOPLASTIC FILAMENT HAVING A TWO PHASE CROSS-SECTION 3 Sheets-Sheet 5 LOAD 8 IO l2 l4 l6 LENGTH OF TEST PIECE UNDER TENSION IN cm United States Patent US. Cl. 161-173 11 Claims ABSTRACT OF THE DISCLOSURE An improved crimped filament of thermoplastic synthetic high polymer of the invention is composed of nonconjugated structure having two different phases in cross section of said filament. The above-mentioned two different phases in cross section of the filament is defined by the difference in dyeability or refraction index. The crimped filament of the invention is provided with the outside roughened surface having numerous fine pit-like portions. The process for manufacturing the crimped fiber of the invention is also disclosed.

This invention relates to an improved crimped filament and a process for manufacturing the same particularly relates to a crimped filament composed of two different phases of structure with a synthetic linear high polymer, such as polye-caproamide, etc., and a process for manufacturing the same.

The so-called textured filament yarn, such as Agilon which is produced by passing the stretched filaments over a sharp edge in such a manner that the threadline of the filaments is deflected at an angle at the deflecting edge and then the filaments are allowed to shrink, is one of the well-known textured filaments composed of non-conjugated structure comprising a high-shrunk portion and a low-shrunk portion.

Another type of the filament yarn composed of potentially crimpable filaments of linear high polymers can be produced by prior arts, for example, according to British Pat. No. 939,314, wherein the filaments Which are stretched in a continuous manner to two to eight times their original length are subjected to a short heat treatment such that the filaments are heated on one side for a very short time by passing the filaments at a speed of over 100 m./min. over a small hot surface having a temperature within the range of 300 to 900 C. to deflect the threadline of the filaments sothat the portion of the filaments approaching the hot surface forms an angle within the range of 130 to 170 with the portion of the filaments leaving the hot surface.

The crimped filament yarns of the first case have a somewhat stiff feeling when one touches the woven or knitted materials manufactured with this filament yarn, while those of the second case have poor elasticity, further there is possibility of troubles such as yarn breakage during the manufacturing process.

The principal object of the present invention is to provide an improved crimped filament of a synthetic linear high polymer having properties suitable for practical end uses such as seamless stockings and knitted goods manufactured by a tricot machine.

The other object of the present invention is to provide an improved process for producing potentially crimpable filament of a synthetic linear high polymer at high efficiency and low cost.

Generally, synthetic filament has a smooth surface, whereby so-called metallic luster of the filament is in- 3,fifi0,27i Patented Aug. 17, 1971 ice evitable. To provide a soft luster to the filament, a pigment such as titanium dioxide has been added to the polymer. However, it is clear that addition of a pigment to the polymer degrades the mechanical properties of the filament produced.

A further object of the present invention is to provide a high bulky crimped filament having soft and elegant luster from a synthetic linear high polymer even if some kind of pigment has been added.

Recently, the so-called composite filament composed of two or three different high polymers have been developed. It is said that the crimped filament yarns of the second case have inferior properties such as poor crimp recovery, durability of crimps and crimpability when compared with the third case, even if the freedom for selecting the fineness of filament and the size of crimp is better than the third case.

It is a further object of the invention to eliminate the defect of the third case by the improved crimped filament of the present invention.

Further objects and advantages of the present invention will be apparent from the following description, with reference to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

FIG. 1 is an embodiment of the process for manufacturing crimped filaments from a synthetic linear high polymer according to the invention,

FIGS. 2A and 2B are enlarged sketches of the coredyed section of the crimped filaments showing the particular structure of the filament of the present invention,

FIGS. 2C and 2D are enlarged sketches of the coredyed section of the crimped filaments produced by the Agilon method and the process of the British Pat. No. 939,314, respectively, showing the structure of these filaments,

FIG. 3 is an enlarged side view of an embodiment of the crimped filament of the invention,

FIG. 4 is an enlarged sketch of another embodiment of the invention showing the core-dyed sections of the crimped filaments adhering to each other.

FIG. 5 is an explanatory diagram for showing the crimpability of Agilon, composite filament yarn and the filament yarn of the present invention,

FIG. 6 is a diagram for showing elastic recovery of seamless stockings made from the crimped filament of Agilon, British Pat. No. 939,314 and the present invention, respectively.

Referring to FIG. 1, the improved crimped filament yarn of the invention is produced by the following process; the molten high polymer of poly-e-caproamide is extruded from a spinnerete 1, and cooling and solidification of the stream of the melt emerging from the spinneret 1 are accelerated by a current of cool air shown by the arrows. The resulting filament is taken up at a constant speed by a driven mechanism comprising a pinch roll 5 and the 1st Godet roll 6, them the filament 14 is further taken up by drawing rolls 8 by which the filament 2 is stretched in a stretching zone between the first Godet roll 6 and the drawing roll 8. During the stretching operation the filament 14 passes over a heated cylindrical pin 7 which contacts it. Next the stretched filament 14 is taken up on a bobbin 9. In the above-mentioned spinning operation, the oiling operation is applied to the filament by a conventional oil disk 4 and trough as shown in FIG. 1. The surface speeds of the first Godet roll 6 and the second Godet roll 8 are 500 meter per min. and 2,000 meter per min., respectively. The cylindrical pin of 60 mm. dia. is maintained at 600 C. The stretching of the filament is carried out at the contact surface of the filament with the pin 7. The contact portion of the filament 2 is provided with an abrasive action by the pin 7 and further, the contact portion of the filament is provided with a more severe heat treatment than the outside portion of the filament while the filament turning over the pin 7 is maintained at a high temperature such as 600 C. By the abrasive and stretching action heat treatment is applied to the inside portion of the filament and numerous small uneven pit-like portions are formed at the inside surface of the filament while the smooth surface of the filament is maintained at the outside portion of the filament. It was confirmed by microscopic observation after the dyeing treatment that the structure of the filament produced is composed of two dilferent phases of structure with a single polymer. In the drawings of FIGS. 2A and 2B, samples of the above-mentioned test are shown, that is, a test piece of the filament produced is dyed by a dyeing agent (Lanasyn Grey BL 1% aq. at 95-100 C., for 5 min.), then the dyed filament is decolorized by an alcohol solution of 75% concentration for 15 min., then the treated filament is cut to a cross-sectional piece of 5 microns thickness by a conventional method for microscopic test and photomicrographs of the test pieces were taken, as shown in the drawings of FIGS. 2A and 2B. As it is clearly shown in the drawings, the stretched filament 14 produced is provided with a dark colored portion 15 and a rubbed portion 16 which is light in color. The rubbed portion 16 is provided with an uneven surface 16'. To make clear the difference in the structure of the filament according to the present invention and that by the above-mentioned other processes, the filament produced by the process of British Pat. No. 939,- 314 and also by the process of Agilon were tested in the same manner. It is impossible to produce a practical filament having the two different phases of structurewhich is shown in FIGS. 2A or 2B, by the process of British Pat. No. 939,314, that is, filament having above-mentioned two different phases of structure can be obtained only in case of severe condition of operation of British Pat. No. 939,314. However, it is almost impossible to operate the process continuously because of numerous yarn breakage during the operation, moreover, the mechanical properties of filament are poor. The ratio of the occupied area in the cross section, of the portion having roughened surface to that of the cross section of the filament according to the invention is almost %s%. Consequently, the structure of the filament according to the present invention is remarkably different from the conventional crimped filament yarn. To confirm further the detailed structure of the filaments, the structure of the filaments produced by the present invention and the British Pat. No. 939,314 were studied by analysis utilizing the X-ray diffraction X-ray which was generated by an X-ray analyzer at the condition of 30 kv16.5 mv. The ratio of A and B in case the filament of the present invention was more than 0.4, for example, was A/B=0.82 for a filament of 15 d., 0.78 for a filament of d., and 0.73 for a filament of 7 d., while the ratio of A and B in case of the filament of the British Pat. No. 939,314 was below 0.4. The above-mentioned ratio of A and B is defined as follows:

X-ray intensity for (0, 2,0) plane on the meridian Generally, the ratio of A and B for the conventional filament is below 0.1. By the above-mentioned X-ray analysis, it is clear that the filament produced by the invention is provided with a large amount of u-type crystallized portion in comparison with the filaments produced by the other process.

When the filament produced by the present invention is treated by the succeeding process of relaxation under a preferable temperature, the dark colored portion of the filament 14 shrinks to a greater extent than the light colored portion 16 of the filament 14, consequently, the stretched filament 14 of the invention develops curled crimps as shown in the drawings of FIG. 3, in which each curled crimped portion of the filament 14 comprises an outside portion provided with numerous uneven roughened surface while the inside surface is smooth.

An embodiment of the relaxation treatment of the stretched filament is shown in FIG. 1. After taking up the stretched filament 14 on a package 9, the filament 14 is taken from the package 9 by a pair of feed rolls 10, and led to a heat treatment chamber 11 maintained at C. and taken up by a pair of take-up rolls 12. The surface speeds of the feed rolls 10 is considerably faster than that of the take-up rolls 12 so that the stretched filament 14 is provided with relaxation under heat while passing through the chamber 11. Consequently, the filament 14' delivered from the take-up rolls 12 is provided with nu merous curled crimps. Finally, the relaxed filament 14' is taken-up on a package 13 form of a pirn.

There are several methods for indicating the magnitude of the crimp of the filament. In the present invention, the following method was applied, that is, the filament is wound 20 times around a conventional hank reeling machine for testing, then the wound test piece of filament is packed with a cloth. Next, the packed test piece is treated in a boiling water of 98100 C. for 30 minutes. After drying, the elongation in percent to the initial length of the test piece which was measured at the loading condition of 1.2 mg./ d. is obtained under the load of /3 g./denier. The above-mentioned elongation is defined as the elongation of crimp in this specification.

By the following test results, the difference between the structure of the filaments of the present invention and that of the British Pat. No. 939,314 is made clear. For a better understanding, some data of the stretching condition of the filament by the present invention are disclosed in Table 1. Further, the number of uneven portions, angle A defined by the following definition, and the ratio R of the occupied area in cross-section, of the portion having roughened surface to that of the crosssectional area of the filament are shown in the same table. The number of pit-like portions on the roughened surface of the filament which is shown in an enlarged microscopical photograph was counted. In the abovementioned estimation, the projections of the pit-like portions over 0.5 micron were counted.

The angle A is defined as follows. In FIG. 2A, when the center of the cross-section of the filament 14 is X, the crossing points of a line passing an edge of the portion 15 with the outer profile of the cross section of the filament 14 are Y and Z as shown in the drawing, and the angle YXZ is desginated as A.

The elastic recovery (in percent) and other mechanical properties such as breaking strength and elongation, and shrinkage in boiling water (in percent) of the other two types of filament were also measured.

TABLE 1 (1) (2) (3) Test piece (filament) 30d./2 fil. 20d./2 fil. 20.d/4 Ill.

Stretching condition:

Stretch ratio 4.0 4. 0 4. 0 Contact angle wit pm, degrees- 120 120 00 Yarn tension (in g.):

Before contact with pin 3 2 2 After contact with pin 33 23 20 Contact length with pin (in mm.) 63 63 47 Coefl'iclent of friction with pin calculated by Amonton equation 1.15 1.18 1. 47 Number of projections in a roughoned surface of filament in 1 mm. length. 50 60 55 1/4 1/5 1/5 100 100 The mechanical properties of the above-mentioned three filaments of the invention were almost the same but that of the filament produced by the process of British Pat. No. 939,314 is inferior to that of the present invention, as is clearly shown in Table 2.

To find the filament having preferable qualities according to the present invention, several types of filament which differ in the density of the projection in their roughened surface were produced and their mechanical properties such as elongation of crimp (in percent) and li reljlkugg strength (in g.) were compared, as shown in By a further experimental test, it was disclosed that the filament of the invention having more than 20 pit-like portions has sufiicient elongation of crimp and also excellent handling quality, such as superior crisp feeling. However, when the above-mentioned ratio R is more than and the value of A is more than 240, the

strength of the filament is degraded remarkably, as shown in Table 3.

TABLE 3 3 3.3%? 35233? Ratio R in percent in g./den. 55 2 5; 2 to if; E8 52:21:??? than 9 EXAMPLE 1 A filament of poly-e-caproamide of denier was extruded by the conventional method. After cooling and solidification of the melt emerging from the spinneret in the spinning process, the filament produced was oiled. Within 30 seconds after the oiling operation, the filament was passed over a heated pin of 1 inch diameter in such a way that the contact angle of the filament with the pin was 200, that is, the contact length of the filament with the pin was 6.6 cm. while the temperature of the pm was maintained at 560 C. The filament was stretched at a ratio of 3.8 when the filament was passing on the pin. Then the filament was taken up on a package. The filament produced was provided with two different structures in a single polymer which was confirmed by the dyeing and microscopic test as mentioned already. The ratio of R was almost /3. The filament produced was treated by the relaxation process under 180 C. as shown in FIG. 1, by which remarkable crimps were developed on the filament. To make clear the difference in crimpability between the filament produced and the other conventional textured filament yarns, the following test was performed, that is, test pieces of the filament of the invention and the other textured filament yarns, Agilon and composite filament were maintained at several loading condition in steam of 100 C., and next the length of the crimps was measured under a loading condition of 1.2 mg. The results obtained by the above-mentioned test are shown in diagrams a, b, c of FIG. 5, wherein diagram a represents Agilon, b composite filament, and c filament of the present invention. In the diagram, the abscissa designates load, while the ordinate designates loop length of crimp. Therefore, the diagrams can be interpreted as follows; when the loop length of crimp at any point of the abscissa is smaller, the crimpability of filament can be considered as being stronger. From the above-mentioned test, it Was disclosed that the filament produced by the process of the present invention has superior crimpability in comparison with the other conventional filaments.

EXAMPLE 2 Molten high polymer of poly-e-caproamide is extruded from a spinneret provided with 6 holes; after cooling and solidification of the streams of the melt emerging from the spinneret the multilfiaments produced were separated into three groups, in such a way that each group comprises 2 filaments; next, oiling and then stretching were applied to the separated multifilaments. While stretching the filaments, they were contacted with a heated pin of 60 mm. in diameter in such a manner that the groups of multifilaments pass along the separated passage of the pin heated at 620 C. Then the stretched filaments were doubled and taken up on a package. The total denier of the multifilament was 30 denier. Crimped yarn comprising uniform and fine coiled multifilaments were manufactured by a relaxation treatment such as the process explained in the embodiment shown in FIG. 1.

The multifilament produced comprises three groups of two filaments of 5 denier which adhere to each other at their contact portions as shown in FIG. 4, further when the multifilament of this embodiment is observed microscopically as explained in the explanation of the drawing, the dark colored portions 15 of the two filaments 14 are arranged on the same side while the light colored portion 16 provided with the roughened surface are arranged on the other side. This is also one of the remarkable features of the multifilament produced by the present process. Consequently, the multifilaments produced by the present invention are always composed of numerous filaments provided with uniform crimples, and it is possible to produce textile goods having an excellent handling quality, such as resilient and crisp feeling, according to the present invention.

EXAMPLE 3 Stockings were made with the crimpable filament of 15 denier produced by the process explained in Example 1, the filament produced by the process of British Pat. No. 939,314, and Agilon filament. To compare the elastic recovery of the above-mentioned three stockings, the respective load-elongation hysteresis diagram of the abovementioned stockings were obtained with an Instron Tester and are shown in FIG. 6. The test piece was 10 cm. long, and after extension of the test pieces to 17 cm. length at a stretching speed of 20 cm./min., they were unloaded at the same speed as that of the stretching. As shown in the drawings of FIG. 6, the stocking made by the filament of the present invention has excellent elasticity, that is, it was necessary to stretch the test piece with a strong tension at its low elongation, while it is only necessary to stretch the test piece with a weak tension at a high elongation and the elastic recovery of the stocking is fairly excellent in comparison with the other stockings. In FIG. 6, d designates a stocking made by the filament produced by British Pat. No. 939,314, e designates a stocking made by Agilon and f designates a stocking made by the process of the invention. Consequently, the handling quality of the stocking made by the filament of the present invention is excellent and has sufficient strength.

While the invention has been described in conjunction with certain embodiments thereof it is to be understood that various modifications and changes may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. An improved crimped filament of thermoplastic synthetic high polymer composed of non-conjugated structure having two different phases in the cross section of said filament defined by the difference in dyeability or refractive index, the outside of the crimps of said filament provided with the roughened surface, said roughened surface provided with numerous, fine, pit-like portions, the depth of said pit-like portions is from 0.5 micron to 10 microns, and the number of said pit-like portions is more than 20 per 1 mm. length of filament.

2. An improved crimped filament of thermoplastic synthetic high polymer according to claim 1, further characterized by a portion of said two difierent phases in the cross section of said filament having the ratio X/ Y of the area of said two phases from /8 to /1, wherein X designates the area of the portion provided with said roughened surface, Y designates the cross sectional area of said filament.

3. An improved crimped filament of thermoplastic synthetic high polymer according to claim 2, wherein said thermoplastic synthetic high polymer is poly-e-caproamide.

4. An improved crimped filament of thermoplastic synthetic high polymer according to claim 3, wherein the elongation of crimp is 40% to 50% and the elastic recovery of elongation is 80% to 90%.

5. An improved crimped filament of thermoplastic synthetic high polymer according to claim 4, wherein the breaking strength is 4 to 5 grams per denier.

6. An improved crimped filament of thermoplastic synthetic high polymer according to claim 1, further characterized by a geometrical angle A of said roughened surface in the cross section of said filament with respect to the center of said cross section from 45 to 240, wherein, when the center of the cross section of the filament is x, the crossing points of a line passing an edge of the boundary portion with the outer profile of the cross section of the filament are y and z, the angle yxz is designated as A.

7. An improved crimped filament of thermoplastic high polymer according to Claim 6, wherein said thermoplastic synthetic high polymer is poly-e-caproamide.

8. An improved crimped filament of thermoplastic synthetic high polymer according to claim 1, further characterized by said filament being multifilament comprising a plurality of fine filaments, wherein at least two component filaments adhere to each other at their longitudlnal linear portions, and said roughened surface of each filament is developed on the same side with respect to their adhered portions.

9. An improved crimped filament of thermoplastic synthetic high polymer according to claim 8, wherein said thermoplastic high polymer is poly-e-caproamide.

10. An improved crimped filament of thermoplastic synthetic high polymer according to claim 1, wherein said thermoplastic synthetic high polymer is poly-ecaproamide.

11. An improved crimped filament of thermoplastic synthetic high polymer according to claim 10, further characterized by a structure of said filament defined by the ration of A/B being over 0.4, wherein said A refers to X-ray intensity for (0,2,0) plane on the meridian, B refers to X-ray intensity for 20:23.7 on the equator.

References Cited UNITED STATES PATENTS 3/1961 Speakman et a1. 28--1 12/1963 Schmeider et al 2872.l3

FOREIGN PATENTS 939,314 10/1963 Great Britain.

U.S. Cl. X.R. 

